The subject of the invention is a filler neck for a fuel tank of a motor vehicle, with vent lines and valves arranged in addition to the filler pipe.
Filler necks for fuel tanks of motor vehicles are generally known. In addition to the actual filler pipe for introducing fuel into the fuel tank, current filler necks have additional lines and compensating reservoirs for venting the fuel tank while the motor vehicle is being refueled and operated. Furthermore, filler necks often have valves, such as, for example, roll-over valves, switching valves and safety valves.
It is known to produce filler pipes for fuel tanks by the blow molding method and subsequently to mount the vent lines and the valves, together with the filler pipe, on the filler neck. For this purpose, the vent lines have to be laid in place and connected to the filler pipe. The necessary valves likewise have to be connected to the corresponding lines. A filler neck of this type possesses a multiplicity of individual parts and connections and therefore requires a high outlay in terms of assembly. Moreover, the high fuel permeation due to the connections on the filler neck is also particularly disadvantageous.
It is also known to produce vent lines in one piece with the filler pipe by the blow molding method, the vent lines being connected only on the circumference to the filler pipe and separately to valves or to the fuel tank. In this design, too, filler necks still have high permeation values. Finally, because of poor access, the valves are also complicated to mount when they are subsequently built into the blow-molded filler pipe.
Improved mounting is made possible by a filler pipe which is produced by the injection molding of two half shells. In this design, a valve can be mounted into the half shells before these are welded together.
The object on which the invention is based is to provide an easily mountable filler neck which has low permeation values.
The filler neck according to the invention comprises of at least two interconnected injection-molded half shells, each half shell possessing a plurality of outwardly curved regions. In the connected state, these outwardly curved regions produce individual chambers of the filler neck. These chambers form the filler pipe, the operational vent line, the tank vent line or further lines of the filler neck. Furthermore, at least one chamber, preferably the chamber forming the filler pipe is designed for connection to another component, in particular the fuel tank. Moreover, receptacles are integrally formed in the outwardly curved regions of the half shells, in order to arrange structural elements in the filler neck.
The essential advantage of this filler neck is that all the lines, valves and other structural elements are now arranged in the half shells. The filler neck therefore does not have any other connection points, apart from the connection to the fuel tank, so that very low permeation values are achieved. Also, this filler neck makes very simple mounting possible, since the structural elements, for example roll-over valve, backwash valve, vent valve, can be mounted in the individual half shells prior to assembly.
Advantageously, the half shells of the filler neck are welded to one another. However, all other connections leading to a permanent and leaktight composite structure of the half shells may also be envisaged. In this case, the filler neck according to the invention can be produced particularly easily if the half shells are connected to one another on their end faces. The half shells can be connected particularly simply if all the end faces lie in one plane.
In another development, not all the end faces lie in one plane. It may be advantageous to provide one or more end faces of a half shell so as to be elevated out of the plane of the other end faces, so that these elevated end faces, when being connected to the other half shell, reach into an outwardly curved region of the other half shell. What is achieved thereby is that, when the half shells are welded together, this elevated end face subdivides the outwardly curved region of the other half shell into two chambers.
Furthermore, it may be advantageous, depending on the geometry of the filler neck, if the filler neck is formed from three or more half shells. As a result, despite the filler neck having a complicated shape, the half shells can be produced by means of relatively simple molding dies.
It is advantageous if the half shells have integrally formed on them connecting and catching elements. By means of these, the structural elements can be fixed in the half shells particularly simply. There is therefore no need to have additional fastening means for the structural elements.
In an advantageous development, the filler neck is particularly small if the vent lines are not formed as chambers in the half shells, but are produced in them by the gas internal pressure method (GID). For this purpose, when the half shells are being produced, a gas is injected in one region of the plasticized plastic and, by means of its pressure, inflates the plastic material, thus providing a cavity which forms the subsequent line. These GID lines may, in turn, open again into a chamber. The vent lines can thus be arranged particularly simply, for example, in the wall of the chamber forming the filler pipe.
In a further advantageous development, these GID lines, on the one hand, open into the filler pipe, whilst, at their other end, they open into further chambers, in which, for example, valves are arranged. The advantage of this design is that the vent lines are led out of the fuel tank through the lower region of the filler pipe and are then connected to the corresponding GID lines. The filler neck according to the invention therefore requires only one point of connection to the fuel tank, thus likewise contributing to a marked reduction in permeation.
In a further advantageous development, a filter for the gases to be discharged through the vent lines is integrated into the filler neck. For this purpose, the filler neck possesses a further line leading from the vent lines to a region in which the filter, preferably an activated charcoal filter, is arranged. The filter may, in this case, be arranged at any desired point on the filler neck. The purified gases are conducted to the atmosphere via a shutoff valve which is likewise arranged in the filler neck and which is provided for leak diagnosis in order to check the leak-tightness of the tank.
In another development, a chamber in the half shells forms the filter housing, so that only the filter material has to be arranged in this chamber. The filter can consequently be adapted more closely to the existing geometry of the motor vehicle, and no space is required for a separate arrangement of the filter. The line to the filter is also dispensed with. Arranging the filter in the filler neck likewise contributes to reducing the permeation.
It is also advantageous to arrange in the half shells, instead of the receptacles for the valves, parts of the valves, for example the housing and valve seat, in that these parts are integrally injection-molded onto the half shells.